1. Field of the Invention
The present invention relates to a fuel injector for increasing a pressure of fuel within a fuel tank by a fuel pump and feeding the boosted fuel through a fuel injection valve arranged in a fuel distribution pipe.
2. Description of the Conventional Art
A fuel injector is composed of a throttle body, a fuel distribution pipe provided with a fuel injection valve, a fuel pump, a fuel pressure controlling valve, a filter and the like. Among these components, the fuel pump, the fuel pressure controlling valve and the filter as a fuel pressure increasing portion, a fuel pressure controlling portion and a fuel filtering portion respectively, are received and disposed in a single fuel case in view of the mountability to a vehicle, assembling property and compactness. For example, this is disclosed in Japanese Patent Application Laid-Open No. 11-108700 applied by the present applicant.
An object of the present invention is to provide a fuel feeding device for a fuel injector in which a fuel pump, a fuel pressure controlling valve and a filter are arranged in a single fuel case, that can stably feed an accurately measured fuel for a long period of time through a fuel injection valve and stably control the pressure controlling characteristics of the fuel pressure controlling valve for a long period of time.
In a fuel feeding device for a fuel injector according to the present invention, in order to attain the above mentioned objects, a fuel case is partitioned to form, from one side to the other, a fuel introduction chamber, to which a fuel introduction passage is opened, a pump receiving chamber for receiving a fuel pump, and a fuel discharge chamber, to which a fuel discharge passage is opened and which receives a filter; an intake passage of the fuel pump disposed in the pump receiving chamber is opened to the fuel introduction chamber and a discharge passage of the fuel pump is in direct communication with an inside of the filter disposed in the fuel discharge chamber; a fuel pressure controlling valve is partitioned into a spring chamber and a fuel chamber by a diaphragm, a fuel introduction passage is opened to the fuel chamber, and a fuel return passage that is opened and closed by a valve that moves synchronously with the diaphragm is opened to the fuel chamber; an upstream of the fuel introduction passage of the fuel pressure controlling valve and an upstream of the fuel discharge passage are disposed to be opened in a cleaned fuel discharge chamber formed by an inside of the fuel discharge chamber and an outside of the filter; the fuel chamber of the fuel case is in communication with the fuel tank and the fuel discharge passage of the fuel case is in communication with a fuel distribution pipe provided with a fuel injection valve; the fuel return passage is in communication with a fuel tank through a pump receiving chamber and a discharge passage.
Fuel in the fuel tank is sucked into the fuel pump through a fuel introduction passage provided in the fuel case and a suction passage of the fuel pump, and the fuel whose pressure has been boosted by the fuel pump is fed directly from the discharge passage of the fuel pump to the inside of the filter received and disposed in the fuel discharge chamber. A foreign matter in the fuel is removed by the filter and the cleaned fuel discharge chamber formed by the inside of the fuel discharge chamber and the outside of the filter is thus filled with the clean fuel. Then, a part of the clean fuel in the cleaned fuel discharge chamber is fed into the fuel chamber of the fuel pressure controlling valve through the fuel introduction passage of the fuel pressure controlling valve and the remaining part of the clean fuel in the cleaned fuel discharge chamber is fed to the fuel distribution pipe through the fuel discharge passage.